1. Field of Invention
The present invention relates to a circuit for processing display data, and more particularly to an apparatus and a method for generating overdriving values for use in LCD overdriving.
2. Description of the Related Art
When a flat panel display such as an LCD is displaying a frame image, each pixel within the display is applied with a driving voltage to rotate the liquid crystal molecules, which changes the light transmissivity of the pixel to produce expected brightness and color. The rotation speed and rotation angle are related to the applied driving voltage; the larger the driving voltage, the higher the rotation speed is and the larger the rotation angle after reaching a stable state is. To operate the display at a frame rate of 30 fps or higher, for example, the pixel needs to be applied with an overdriving voltage, so as to speed the rotation of the liquid crystal molecules and the transition to next frame image. To this end, a look-up table (LUT) is used to find out an overdriving value corresponding to the overdriving voltage for application to the pixel according to its initial grayscale value and target grayscale value for the next frame image.
FIG. 1 is a block diagram of a conventional apparatus for generating overdriving value corresponding to an overdriving voltage for application to a pixel of the display and FIG. 2 is an LUT used in the conventional apparatus as shown in FIG. 1. Refer to FIGS. 1 and 2, an LUT storage 15 receives the target grayscale value VT and the initial grayscale value VS stored in a frame buffer 13 and outputs the overdriving value VOD corresponding to the overdriving voltage of the pixel for application to the pixel to speed the frame transition. For example, in FIG. 2, if the initial grayscale value VS is 111 and the target grayscale value VT for the next frame image is 127, the corresponding overdriving value VOD of 133 is found out.
However, such a conventional LUT ignores two factors, that is, frame rate and temperature, which would affect accuracy of the overdriving values and the credibility of the LUT. In a computer game demanding a display operated at a frame rate of 120 fps, for example, using such a conventional LUT to get the overdriving values often fails to rotate the liquid crystal molecules and transition to the next frame image timely and sufficiently, thus degrading the display quality.
Therefore, there is a need to improve the conventional apparatus, so the display quality can be effectively improved.